Method and apparatus for producing a filter rod for smoking articles

ABSTRACT

An apparatus for continuous production of a filter rod for smoking articles includes a belt conveyor system for advancing a rod of filter material. The belt conveyor system has separate conveyor belts, having respective upper conveying runs arranged one downstream of the other. Speeds of the conveyor belts are controlled according to a predetermined ratio, which controls an axial stretching or compacting effect of the material of the filter rod from the transition between conveyor belts, to influence the characteristics of the produced filter rod. Additional operations can be performed in the area between the upper runs of the conveyor belts, which modify the configuration and/or structure of the filter rod, including shaping, marking or embossing of the filter rod; or filter material may form a filter rod outer layer. The apparatus can produce a filter rod having a coaxial configuration.

FIELD OF THE INVENTION

The present invention relates to methods and apparatus for continuousproduction of filter rods for smoking articles, of the type in which abelt conveyor system is provided for advancing a rod of filter materialalong a forming path, and in which said belt conveyor system comprisesat least one endless belt, having an upper conveying run for conveyingthe filter rod.

PRIOR ART

Since long, apparatus of the aforementioned type have been known, whichare for producing filter rods consisting of a filter material (typicallycellulose acetate) and having no outer wrapping sheet. These filter rodsare to be divided into sections of predetermined lengths to formnon-wrapped cellulose acetate or “NWA” filter segments.

A machine of the aforementioned type is described and illustrated inEuropean Patent EP 2 636 321 B1 of the same Applicant. In apparatus ofthis type, the filter rod is advanced along the forming path by means ofa belt conveyor system including a single endless belt, the upper run ofwhich is in direct contact with the filter rod.

The use of a transport system has also been proposed in the past (U.S.Pat. No. 6,932,752 B2) that includes two endless conveyor belts,arranged one downstream of the other, in an apparatus for producingmulti-component filter rods, in which a succession of filter segments iswrapped within an outer wrapping sheet. In this known solution, theprovision of two conveyor belts has been proposed simply to avoid theelongation and side movement to which a single conveyor belt issubjected to, and to enable control of the tension state of the wrappingsheet that is interposed between the transport belts and the filtersegments.

A solution with more conveyor belts is also known from document EP 1 872673 A1.

OBJECT OF THE INVENTION

Starting from the above-mentioned known solutions, the Applicant hasbeen faced with the problem of producing an apparatus and a method forproducing filter rods that provides an improved control on the qualityand characteristics of the finally obtained product.

SUMMARY OF THE INVENTION

In view of achieving the aforesaid object, the invention relates to amethod of the type indicated at the beginning of this description, inwhich a filter rod is advanced along a forming path, characterized inthat the aforesaid belt conveyor system comprises at least two separateconveyor belts, having respective upper conveying runs arranged onedownstream of the other along said forming path and in that, in the areabetween the upper runs of said at least two conveyor belts, an operationis carried out that modifies the configuration and/or structure of thefilter rod, such as shaping of the filter rod cross-section and/orembossing and/or marking of the surface of the filter rod and/orsupplying filter material to form an outer layer of the filter rodand/or shaping of a wrapping sheet of the filter rod. Further examplesinclude a drying operation or providing an additive material, such as adye or flavoring material, for example in the form of microcapsules, oran outer coating material.

“Forming path” in this description, and in the following claims, meansthe path that starts from the inlet of the filter rod forming channeland terminates with a cutting device that is conventionally used alongthe production line to divide the filter rod into pieces ofpre-determined lengths.

In a preferred embodiment, the material constituting the filter rod (M)is without an outer wrapping sheet. In the case of this application, afurther aspect of the invention, which can either be adopted in additionto or alternatively to the above-mentioned solution, is directed to amethod of the type indicated at the beginning of this description, inwhich a rod of filter material is advanced along a forming path,characterized in that the aforesaid belt conveyor system comprises atleast two separate conveyor belts, having respective upper conveyingruns arranged one downstream of the other along said forming path, andin that that the movement speeds of said conveyor belts are controlledaccording to a predetermined ratio, said predetermined ratio beingselected so as to obtain a controlled axial stretching effect or acontrolled axial compacting effect on the material of the filter rod, asa result of the transition from one conveyor belt to the other, so as toinfluence the characteristics of the obtained filter rod in the requiredmanner.

The Applicant has, for the first time, found that applying a double-beltconveyor system to a method for producing filter rods with no outerwrapping sheet allows control of the configuration and quality of thefinal product to be obtained with extremely simple and effective means.

In this embodiment, control of the ratio between the movement speeds ofthe two conveyor belts is exploited to modify the configuration and/orstructure of the filter rod. If the downstream belt is driven at agreater speed than the upstream belt, elongation of the product isobtained. If the downstream belt is driven at a lower speed than thespeed of the upstream belt, compaction of the product is obtained.

As already mentioned above, in the prior art, the provision of twoconveyor belts was proposed solely with reference to multi-componentfilter rods including a succession of filter segments wrapped in awrapping sheet. In these known solutions, the control of the speed ofthe conveyor belts had, at most, only the benefit of controlling thetension of the tape of wrapping material of the filter segments. In thecase of the present invention, instead, controlling the speeds of theconveyor belts allows, for the first time, the characteristics of thefinal product to be influenced as desired, producing the required axialstretching or required axial compacting on the filter rod that advancesalong the forming path.

In a further embodiment, in the area between the upper runs of said atleast two conveyor belts, an operation is performed that modifies theconfiguration and/or the structure of the filter rod, such as shaping ofthe filter rod cross-section and/or embossing and/or marking of thefilter rod surface and/or feeding of filter material to form an outerlayer of the filter rod.

More generally, the transition area from one conveyor belt to the otheris used to carry out any further operation on the filter rod materialwithout having any hindrance due to the presence of the conveyor belt.

In a further embodiment, the product quality is influenced bycontrolling the ratio between the speeds of the two conveyor belts andby operating on the rod material in the area interposed between theupper runs of the two conveyor belts.

In the case in which the intermediate station between the two conveyorbelts involves feeding a layer of material, it is also possible toenvisage that the rod fed along the upstream conveyor belt is providedwith a wrapping sheet, and that, conversely, the downstream belt is notassociated with any wrapping sheet, so that the final rod obtained is,however, without any outer wrapping sheet.

The method according to the invention can also be used, in particular,for producing a filter rod with a coaxial configuration structure,comprising an outer layer of filter material, without an outer wrappingsheet, and an inner body in the form of a paper or cardboard tube, or aninner body of filter material.

The present invention also relates to the apparatus used to implementthe method of the invention, according to that indicated in attachedclaim 6.

Naturally, although the embodiments described herein refer to twoconveyor belts, there is nothing to exclude that the apparatus and themethod according to the invention can provide more than two conveyorbelts, according to the needs of each specific application. In addition,along the upper run of each conveyor belt, all necessary operations towhich the filter rod material is to be subjected can be carried out,such as vapor insufflation operations, in order to activate a hardeningagent (typically triacetin) previously added to the materialconstituting the filter rod, and/or drying operations, to causesubsequent hardening of the filter rod, or any subsequent operation,such as the addition of flavoring material.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Further characteristics and advantages of the invention will becomeapparent from the description that follows with reference to theattached drawings, provided purely by way of non-limiting example,wherein:

FIG. 1 is a diagrammatic side view of an apparatus according to theprior art known from document U.S. Pat. No. 6,932,752 B2,

FIG. 2 is a diagrammatic perspective view of a first embodiment of theapparatus according to the invention,

FIG. 3 is a diagrammatic perspective view of a second embodiment of theapparatus according to the invention,

FIG. 4 shows an example of a filter rod with a coaxial configuration,which can also be obtained by the method and the apparatus according tothe invention, and

FIG. 5 is a diagram of the two successive operating steps provided in anembodiment of the method according to the invention, in order to producethe product of FIG. 4.

As indicated above, FIG. 1 illustrates a diagrammatic side view of anapparatus according to the prior art known from document U.S. Pat. No.6,932,752 B2. This document shows an apparatus usable for producingmulti-component filter rods, in which a plurality of filter segments 24are fed in succession above a tape of wrapping paper 18, which isunwound by a reel 16 and is fed above a belt conveyor system, includinga first conveyor belt 56 and a second conveyor belt 58 arranged onedownstream of the other. The upper runs of the two endless conveyorbelts 56, 58 are engaged by means of guide devices 52, 54, which wrapthe upper runs of the belts and the paper sheet 18 fed above them so asto give them a U-shaped cross-section (at the guide device 52) and thena closed circular cross-section (in the second guide device 54). In thisknown solution, the speed of the downstream belt 58 is expected to beslightly higher than that of the upstream belt 56 in order to ensure thecorrect tensioning of the paper tape 18 which wraps around the filtersegments 24.

As has already been indicated above, the present invention has beenoriginated from finding that the application of a double-belt conveyorsystem (known only in the field of equipment for producingmulti-component filter rods, of the type illustrated in FIG. 1) to theproduction of filter rods with no outer wrapping sheet, opens the doorsto conceiving an invention that allows, for the first time, thecharacteristics and the quality of the final product obtained to beinfluenced in an extremely simple and effective way.

However, the invention can also be applied to filter rods with which awrapping sheet is associated, in which case the solution idea describedherein is used, for example, to obtain a required shaping of thewrapping sheet (for example, a tubular shape with circular cross-sectionof a relatively rigid crimped sheet).

A first example of the apparatus according to the invention is shown inFIG. 2. This figure essentially refers to an apparatus of the type thatwas the subject of prior European patent EP 2 636 321 B1 by the sameApplicant, the main difference being that, in this case, the beltconveyor system includes, instead of a single endless conveyor belt, twoendless conveyor belts 1, 2 arranged one downstream of the other. Inparticular, the two conveyor belts 1, 2 have their upper runs alignedand arranged one downstream of the other, along the forming path F of afilter rod M. The material constituting the filter rod M is fed to theinlet of the forming channel F by means (not shown) of any known type.

According to a conventional technique (see, for example, EP 2 636 321B1), the material constituting the filter rod M is advanced throughsuccessive processing stations, which may include, for example, astation S1 for vapor insufflation, having the function of activating thehardening agent (triacetin) that was previously added to the filtermaterial M, and subsequent stations S2, S3 for stabilizing the filterrod, of any known type.

The details of construction of the stations S1, S2, S3 are not providedhere, since, as already indicated, these stations can be made accordingto any known art, and as they do not fall, taken alone, within the scopeof the present invention. Furthermore, eliminating these details fromthe drawings makes them more readily and easily understandable.

According to the prior art, when crossing each station, the upper tapeof each belt meets a guide device that is configured so as to force thebelt to deform laterally, in order to assume a U or O cross-section.However, the case is not excluded that this is implemented only for theupstream belt, which forms the filter rod, while the downstream belt canbe left undeformed, with a planar configuration.

Each endless belt is engaged on a plurality of idler rollers R and on adriving wheel P, which actuates the movement of the respective conveyorbelt by means of direct frictional contact with it. In the exampleillustrated in FIG. 2, the two driving wheels P are controlled inrotation by respective electric motors M1, M2 (shown onlydiagrammatically in the drawings, and optionally including respectivegear reducing units), said electric motors being, in turn, controlled byan electronic control unit E.

It is, however, evident that the driving system for moving the conveyorbelts can be completely different from that illustrated in FIG. 2 purelyby way of example. For example, a single electric drive motor could beprovided with transmission devices that connect the single drive motorto the two conveyor belts, and which can be controlled by the electroniccontrol unit.

In the first embodiment of the present invention illustrated herein, therotation speeds of the motor wheels P are controlled according to apredetermined ratio, which can be different from 1. This predeterminedratio is selected so as to influence the characteristics of the filterrod M in the required manner. In particular, the speed of the downstreambelt 2 can be increased or decreased with respect to the speed of theupstream belt 1, in order to obtain a controlled axial stretching or acontrolled axial compacting of the material M constituting the filterrod. In fact, since the upper runs of the two conveyor belts 1, 2 are infrictional contact with the material M constituting the filter rod, theyare able to influence the axial elongation or compacting of the rodduring transition from one belt to the other, through the programmedcontrol of the respective transport speeds.

This result is completely unreachable in known devices of the type shownin FIG. 1, where control of the speed of the conveyor belts can, atmost, influence the degree of tensioning of the wrapping tape of thefilter segments in a multi-component filter rod.

Naturally, the friction between the filter rod material and the conveyorbelts depends, in particular, on the area of the contact surface betweenthe rod and each belt, and on the roughness of the contact surfaces. Thecontact area is more extended in the case in which the belt is forced towrap partially or completely around the rod when crossing the processingstations S1, S2, S3. The belt surface can be prepared with a texturethat increases friction. The skilled technician can then take advantageof these arrangements to achieve the desired result.

FIG. 3 shows an embodiment where the transition area from one conveyorbelt to the other can be exploited to carry out any further operation onthe filter rod material that requires the absence of the obstacle due tothe presence of a conveyor belt. In the case illustrated in FIG. 3, inthe transition area from the conveyor belt 1 to the conveyor belt 2,embossing rollers 3 are provided, which give an embossed configurationto the surface of the filter rod. Of course, the presence of twoseparate conveyor belts makes it possible to take advantage of thetransition area from one belt to the other, in order to carry out anykind of further processing, for example, shaping of the filter rodcross-section, or a marking operation, or adding flavoring material, oradding an outer layer of filter material around the filter rod. Theprovision of two separate conveyor belts, therefore, also provides thepossibility to influence the configuration and structure of the productby arranging product processing stations in the transition area betweenthe upper runs of the conveyor belts.

In the case in which the intermediate station between the two conveyorbelts is for feeding a layer of material, it is also possible toenvisage that the rod fed along the upstream conveyor belt is providedwith a wrapping sheet, as long as the downstream belt is, however, notassociated with any wrapping sheet, so that the final rod obtained is,in any case, without any outer wrapping sheet.

The method according to the invention can also be used, in particular,for producing a filter rod with a coaxial configuration structure,comprising an outer layer of filter material, without an outer wrappingsheet, and an inner body in the form of a paper or cardboard tube, or aninner body of filter material.

FIG. 4 of the attached drawings shows an example of a filter rod M ofthis type, with a hollow inner tube T made of paper or cardboard, and anouter layer R1 of filter material, without an outer wrapping sheet.

FIG. 5 diagrammatically shows two successive steps of the forming methodof the rod M of FIG. 4. In a first step, a wrapping tape W of paper orcardboard is carried by a reel RE, and guided and wrapped around a coreC to form the tube T. In a second step, produced downstream in the line,filter material is fed around the tube T to produce the outer layer R1,without an outer wrapping sheet. In the illustrated example, the filtermaterial is fed around the tube T by means of two conventional-type feeddevices or jets J, which are configured to receive a cord of filtermaterial (illustrated as a cross-section in the drawing) and to feed itwith the aid of a flow of compressed air around the tube T. In FIG. 5,for simplicity and clarity, neither the forming channel nor the conveyorbelts are illustrated.

In an embodiment of the method according to the invention, theoperational steps illustrated in FIG. 5 are implemented by arranging thetwo conveyor belts 1 and 2 in association with the two sectionsindicated with B1 and B2, respectively, in FIG. 5. Therefore, in thiscase, the upstream conveyor belt 1 has its upper run that receives thetape W above it and advances it through the conventional guide device(not shown), which wraps it in order to form the tube T. The stationwith feed devices J for the filter material is arranged in the areainterposed between the upper runs of the two conveyor belts 1 and 2(similar to the one shown in FIG. 3). The upper run of the downstreamconveyor belt 2 comes into direct contact with the outer layer R1 offilter material, and advances the filter rod thus formed through theforming channel and towards the cutting station.

The same solution could be adopted by replacing the tube T with an innerbody of filter material, fed at the inlet of the forming channel andabove the upper run of the conveyor belt arranged further upstream. Theinner body of filter material may or may not have a wrapping sheet, butit is understood that this sheet is, however, covered by the outer layerof filter material.

Also included in the present invention are a method and an apparatuswhich only rely on the provision of one or more product processingstations in the transition area between the upper runs of the conveyorbelts, with equal speeds of the two conveyor belts.

The electronic control unit E is programmed in any predetermined mode,depending on the characteristics of the final product to be obtained.The apparatus according to the invention thus enables a modification ofthe characteristics of the final product obtained with extremely simple,effective and inexpensive means.

Naturally, without prejudice to the principle of the invention, thedetails of construction and the embodiments may vary widely with respectto those described and illustrated purely by way of example, withoutdeparting from the scope of the present invention.

1. A method for continuous production of a filter rod for smokingarticles, said method comprising providing a belt conveyor system foradvancing a rod of filter material along a forming path, wherein saidbelt conveyor system comprises at least one endless belt having an upperconveying run for conveying the filter rod, wherein said belt conveyorsystem comprises at least two separate conveyor belts, having respectiveupper conveying runs arranged one downstream of the other along saidforming path, and wherein in the transition area between the upper runsof said at least two separate conveyor belts, an operation is carriedout that modifies configuration and/or structure of the filter rodcomprising shaping of the filter rod cross-section and/or embossingand/or marking of a surface of the filter rod and/or supplying filtermaterial to form an outer layer of the filter rod and/or shaping awrapping sheet of the filter rod.
 2. A method according to claim 1,wherein the material forming the filter rod is free of an outer wrappingsheet,
 3. A method according to claim 1, wherein speeds of movement ofsaid conveyor belts are controlled according to a predetermined ratio,said predetermined ratio being selected to obtain a controlled axialstretching effect or a controlled axial compacting effect on thematerial of the filter rod as a result of transition from one conveyorbelt to the other, to influence characteristics of the produced filterrod.
 4. A method according to claim 1, wherein a rigid wrapping sheet isassociated with said filter rod, wherein shaping is imparted to saidwrapping sheet.
 5. A method according to claim 1, for producing a filterrod having a structure with a coaxial configuration, comprising an outerlayer of filter material, the outer layer of filter material being freeof a wrapping sheet, and an inner body in the form of a tube of paper orcardboard, or an inner body of filter material, wherein in thetransition area between the upper runs of said at least two conveyorbelts, an outer layer of filter material is supplied, wherein thedownstream conveyor belt is in contact with said outer layer of filtermaterial, and the upstream conveyor belt feeds the inner body comprisingsaid tube of paper or cardboard, or of said inner body of filtermaterial.
 6. An apparatus for continuous production of a filter rod forsmoking articles, comprising a belt conveyor system for advancing a rodof filter material along a forming path, wherein said belt conveyorsystem comprises at least one endless belt having an upper conveying runof the filter rod, wherein said belt conveyor system comprises: at leasttwo separate conveyor belts, having respective upper conveying runsarranged one downstream of the other along said forming path, andwherein between the upper runs of said at least two conveyor belts, afilter rod processing station is interposed for carrying out anoperation changing a configuration and/or structure of the filter rod,comprising shaping of the filter rod and/or marking a surface of thefilter rod and/or feeding of filter material to form an outer layer ofthe filter rod and/or shaping an outer wrapping sheet of the filter rod.7. An apparatus according to claim 6, further comprising: a motorassociated with said conveyor belts, to control the movement of eachconveyor belt, and an electronic control unit for controlling saidmotor, and configured to implement a predetermined ratio between speedsof movement of said conveyor belts said predetermined ratio beingselected to obtain a controlled axial stretching effect or a controlledaxial compacting effect on the material of the filter rod as a result oftransition from one conveyor belt to the other, so as to influencecharacteristics of the produced filter rod.
 8. An apparatus according toclaim 6, wherein the material forming the filter rod is free of an outerwrapping sheet,
 9. An apparatus according to claim 6, for producing afilter rod having a structure with a coaxial configuration, comprisingan outer layer of filter material, the outer layer of wrapping materialbeing free of a wrapping sheet, and an inner body in the form of a tubeof paper or cardboard, or an inner body of filter material, whereinbetween the upper runs of said at least two conveyor belts a processingstation for feeding filter material is interposed, to form said outerlayer of filter material, wherein the downstream conveyor belt is incontact with said outer layer of filter material, and the upstreamconveyor belt is arranged to advance said inner body comprising saidtube of paper or cardboard, or said inner body of filter material.
 10. Amethod according to claim 1, wherein a rigid wrapping sheet isassociated with said filter rod, the wrapping sheet comprising a crimpedsheet, wherein shaping is imparted to said wrapping sheet to form acircular cross-sectional tube shape in the transition area.